package netWork;

import com.sun.jdi.PathSearchingVirtualMachine;
import com.sun.jdi.request.InvalidRequestStateException;
import com.sun.tools.javac.Main;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
import java.nio.charset.StandardCharsets;

public class Server {
    private DatagramSocket socket = null;

    public Server(int port) throws SocketException{
        socket = new DatagramSocket(port);
    }

    public void start() throws IOException {
        System.out.println("服务器启动");
        while(true){
            //每次循环，都是一次服务器在接收请求，返回响应的过程
            //1.读取请求，解析请求
            DatagramPacket requestPacket = new DatagramPacket(new byte[4096], 4096);
            socket.receive(requestPacket);
            //字节数组要转成字符串
            String request = new String(requestPacket.getData(),0,requestPacket.getLength());

            //2.根据请求计算响应(回显服务器不需要这一步)
            String response = process(request);
            //3. 返回响应

            //构造一个DatagramPacket作为响应对象
            DatagramPacket responsePacket = new DatagramPacket(response.getBytes(StandardCharsets.UTF_8),
                    response.getBytes().length, requestPacket.getAddress(),requestPacket.getPort());

            socket.send(responsePacket);

            //打印日志：
            System.out.printf("[%s:%d] req: %s,resp: %s\n",requestPacket.getAddress().toString(),
                    requestPacket.getPort(), request, response);
        }

    }

    public static void main(String[] args) throws IOException {
        Server server = new Server(9090);
        server.start();
    }

    public  String process(String request) {
        return request;
    }


}
